


Alternative

by AutisticWriter



Series: Riley's Prompt Meme Fills [47]
Category: Assassination Classroom
Genre: Anal Sex, Bottom Shiota Nagisa, Established Relationship, Explicit Sexual Content, Fluff and Smut, Gift Fic, Injury Recovery, Kissing, M/M, Making Out, Older Characters, One Shot, Post-Canon, Riding, Smut, Swearing, Teasing, Top Akabane Karma
Language: English
Status: Completed
Published: 2019-08-19
Updated: 2019-08-19
Packaged: 2020-09-07 14:50:26
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,359
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20311303
Author URL: https://archiveofourown.org/users/AutisticWriter/pseuds/AutisticWriter
Summary: When Karma breaks his leg, he and Nagisa realise Karma isn’t capable of doing their favourite sex position. So they try something different: Nagisa riding Karma.





	Alternative

Two days ago, Karma fell off of his motorcycle. Not only does he have impressive scratches and bruises all the way up his arm, but his leg is broken, covered in a plaster cast up to the knee. But, being Karma, he doesn’t seem too bothered by it, and keeps grinning like an idiot as he hobbles around on crutches. It’s only when they’re in bed that night that Karma finally realises the limitations of having his injuries.

Karma pulls him closer, wrapping his arm around Nagisa’s back and grabbing a fist of Nagisa’s hair as his boner prods Nagisa in the thigh. Despite his attempts to stay quiet, the feeling of Karma’s arousal makes him groan into Karma’s mouth, and he feels Karma chuckle. His cock throbs, and Nagisa trails a hand down Karma’s back to squeeze his ass. Karma moans and bucks his hips, grinding his erection against Nagisa.

“Fuck, Nagisa…” he groans. “I need to fuck you. I need—wait.”

“What?” Nagisa says. He pulls away and props himself up on his elbow, studying his boyfriend’s flushed face.

“I wanna fuck you, but… I don’t think I can with my leg.”

“Oh yeah…”

He and Karma are pretty vanilla, and prefer the same routine every time they fuck. Karma tops, and fucks Nagisa doggy style, grabbing his hips and making Nagisa come all over the sheets. They do it every time, but it never gets boring, and Karma knows the best way to hit his prostate and make him gasp his name as he comes.

But… with Karma’s leg in a cast and arm aching from the bruises, it would be pretty much impossible to fuck in their normal position.

Going back to kissing Karma, Nagisa thinks hard. As he learned during his assassination training ten years ago, he is very good at detaching his mind from what he is currently doing, so he finds it easy to think whilst Karma pretty much humps his thigh and he sucks on Karma’s bottom lip. He tries to think of the porn he has watched over the years, needing a position where Karma can still be the top but not strain his injured leg… and it comes to him.

He pulls back, and looms over Karma, pressing his hands to the mattress either side of Karma’s shoulders. “I’ve got it. I can ride you.”

Karma stares up at him, and grins. “Good idea. Don’t wanna seem like a lazy jerkass, but can you help me pull my boxers down?”

Nagisa nods, and Karma shifts so he lies flat on his back. He went to bed with only his boxers on, so Nagisa just hooks his thumbs around the waistband and, as Karma raises his hips, he slides them down Karma’s thighs. Karma’s erection springs free, and just the thought of having his cock inside him makes Nagisa shiver.

“Just stay there, and I’ll get the stuff,” Nagisa says, and Karma chuckles.

He darts into the bathroom to locate the lube, and tosses it to Karma. He catches it with his uninjured arm, grinning. Nagisa stands beside the bed and quickly takes his pyjamas off, leaving him in just his briefs. His erection has left a damp patch on the front of them, and Karma snickers. Rolling his eyes, Nagisa pulls off his underwear and gets onto the bed beside Karma.

Karma squeezes lube onto his fingers and grins. “Ready?”

“Sure,” Nagisa says, not sure how to do this.

In the end, he straddles Karma’s hips, and Karma reaches blindly past Nagisa’s cock until he manages to locate his hole. They don’t need much prep and Nagisa has never been one for fingering anyway – not to mention being an experienced bottom – so Karma only takes ten seconds smearing his entrance with lube.

Nagisa takes the lube and covers his hand with some. He grasps Karma’s cock, making Karma grunt at the sudden coldness on his erection, and he grins.

“Don’t grin at me like that,” Karma says.

“Try and stop me,” Nagisa says, and he leans down to kis Karma.

This is totally new; in all the years they’ve been together, Nagisa has never been on top. He always prefers being pressed against the mattress (or couch or wherever else they decide to fuck), a cock buried inside him. To be honest, it never occurred to him that he could still be the bottom, but Karma be the one pressed beneath him. Seeing Karma beneath him like this… it’s hot.

Still, it takes a few seconds for Nagisa to work out what to do. “Okay, I’m gonna grab your cock and then sit down on it. Ready?”

Karma grins. “Go for it.”

With a level of awkwardness that doesn’t suit a former assassin, Nagisa reaches beneath him for Karma’s cock and shifts further up Karma’s prone body until Karma’s erection rubs against his own cock. It makes them both groan, and he smirks. Nagisa lets Karma’s cock rub against his genitals as he moves it, Karma shuddering beneath him, and finally lines it up with his entrance. Nagisa presses down, letting it nudge against his hole, and Karma grunts.

And, carefully, he lowers himself down, letting Karma’s cock slowly slip inside of him. it feels so good and Nagisa clenches himself, making Karma grunt again. He sinks lower, stretching himself with Karma’s cock, and he’s amazed how it can feel so different and yet so familiar. When he is deep enough to feel the head of Karma’s cock nudging his prostate, Nagisa grins down at Karma and starts to fuck himself on his boyfriend’s cock.

He shifts up and down, angling his hips so Karma’s cock hits his prostate every single time, and the pleasure starts to build up.

“Fuck, Nagisa,” Karma groans, thrusting his hips upwards. “Are you gonna go faster, or just sit there all night.”

“All right, Mr Impatient,” Nagisa says, chuckling; when Karma fucks him, he pounds Nagisa as fast as he can. but Nagisa is kind of precarious in this position, so he can’t go nearly as fast as Karma normally does.

So he just takes his time, carefully shifting himself up and down, letting Karma’s cock almost slip out of him before sitting down hard, swallowing it up again. Sweat covers his skin and he pants for breath, amazed how much work is involved. Karma, on the other hand, looks quite relaxed as he lies there, hips twitching as Nagisa fucks himself on his erection. To Nagisa’s relief, none of his injuries seem to be hurting him. Good; that means he can go faster.

Nagisa closes his eyes and picks up his pace, slamming himself onto Karma’s cock and putting immense pressure on his cock again and again. And although he wants this to last longer, it becomes too much and Nagisa cries out as he climaxes, clenching hard around Karma as he comes all over his stomach. He rides the orgasm for several, wonderful seconds, before he opens his eyes. Karma smirks at him.

“You always come first,” he says, teasing.

“How could I not?” Nagisa says, trying to catch his breath as he continues to shift himself, slower this time. “Your cock against my prostate feels so good I can’t last longer. But,” he says, smirking back. “At least I don’t do this” – He clenches himself tight around Karma, and Karma actually yelps – “whenever someone squeezes your cock tight.”

“You bastard,” Karma says, but he laughs.

Karma doesn’t last much longer, letting out a muffled groan as he comes deep inside Nagisa. He feels the heat of Karma’s come pooling inside him, a sensation he always loves. Carefully, Nagisa climbs off of Karma, semen leaking down his thigh. He collapses beside Karma, giving him a kiss.

“How was that?”

“As alternative positions go, it was fucking amazing,” Karma says. “You know, even when my leg’s better, we should do that again sometime.”

Nagisa smiles. “Good idea. Now, I need a shower. Wanna join me?”

“Hell no!” Karma says, remembering how he needs to strap a plastic bag over his cast when he bathes.

Nagisa laughs and gives him a gentle kiss.

**Author's Note:**

> If you want me to write you a short fic, drop in a prompt at my [personal prompt meme](https://archiveofourown.org/collections/AutisticWriters_Personal_Prompt_Meme)!
> 
> [My tumblr](https://anautisticwriter.tumblr.com/).


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